2 * Copyright (C) 1994 Linus Torvalds
4 * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86
5 * stack - Manfred Spraul <manfred@colorfullife.com>
7 * 22 mar 2002 - Manfred detected the stackfaults, but didn't handle
8 * them correctly. Now the emulation will be in a
9 * consistent state after stackfaults - Kasper Dupont
10 * <kasperd@daimi.au.dk>
12 * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont
13 * <kasperd@daimi.au.dk>
15 * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault
16 * caused by Kasper Dupont's changes - Stas Sergeev
18 * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes.
19 * Kasper Dupont <kasperd@daimi.au.dk>
21 * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault.
22 * Kasper Dupont <kasperd@daimi.au.dk>
24 * 9 apr 2002 - Changed stack access macros to jump to a label
25 * instead of returning to userspace. This simplifies
26 * do_int, and is needed by handle_vm6_fault. Kasper
27 * Dupont <kasperd@daimi.au.dk>
31 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
33 #include <linux/capability.h>
34 #include <linux/errno.h>
35 #include <linux/interrupt.h>
36 #include <linux/syscalls.h>
37 #include <linux/sched.h>
38 #include <linux/sched/task_stack.h>
39 #include <linux/kernel.h>
40 #include <linux/signal.h>
41 #include <linux/string.h>
43 #include <linux/smp.h>
44 #include <linux/highmem.h>
45 #include <linux/ptrace.h>
46 #include <linux/audit.h>
47 #include <linux/stddef.h>
48 #include <linux/slab.h>
49 #include <linux/security.h>
51 #include <linux/uaccess.h>
53 #include <asm/tlbflush.h>
55 #include <asm/traps.h>
57 #include <asm/switch_to.h>
62 * Interrupt handling is not guaranteed:
63 * - a real x86 will disable all interrupts for one instruction
64 * after a "mov ss,xx" to make stack handling atomic even without
65 * the 'lss' instruction. We can't guarantee this in v86 mode,
66 * as the next instruction might result in a page fault or similar.
67 * - a real x86 will have interrupts disabled for one instruction
68 * past the 'sti' that enables them. We don't bother with all the
71 * Let's hope these problems do not actually matter for anything.
76 * 8- and 16-bit register defines..
78 #define AL(regs) (((unsigned char *)&((regs)->pt.ax))[0])
79 #define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1])
80 #define IP(regs) (*(unsigned short *)&((regs)->pt.ip))
81 #define SP(regs) (*(unsigned short *)&((regs)->pt.sp))
84 * virtual flags (16 and 32-bit versions)
86 #define VFLAGS (*(unsigned short *)&(current->thread.vm86->veflags))
87 #define VEFLAGS (current->thread.vm86->veflags)
89 #define set_flags(X, new, mask) \
90 ((X) = ((X) & ~(mask)) | ((new) & (mask)))
92 #define SAFE_MASK (0xDD5)
93 #define RETURN_MASK (0xDFF)
95 void save_v86_state(struct kernel_vm86_regs *regs, int retval)
97 struct tss_struct *tss;
98 struct task_struct *tsk = current;
99 struct vm86plus_struct __user *user;
100 struct vm86 *vm86 = current->thread.vm86;
104 * This gets called from entry.S with interrupts disabled, but
105 * from process context. Enable interrupts here, before trying
106 * to access user space.
110 if (!vm86 || !vm86->user_vm86) {
111 pr_alert("no user_vm86: BAD\n");
114 set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | vm86->veflags_mask);
115 user = vm86->user_vm86;
117 if (!access_ok(VERIFY_WRITE, user, vm86->vm86plus.is_vm86pus ?
118 sizeof(struct vm86plus_struct) :
119 sizeof(struct vm86_struct))) {
120 pr_alert("could not access userspace vm86 info\n");
125 put_user_ex(regs->pt.bx, &user->regs.ebx);
126 put_user_ex(regs->pt.cx, &user->regs.ecx);
127 put_user_ex(regs->pt.dx, &user->regs.edx);
128 put_user_ex(regs->pt.si, &user->regs.esi);
129 put_user_ex(regs->pt.di, &user->regs.edi);
130 put_user_ex(regs->pt.bp, &user->regs.ebp);
131 put_user_ex(regs->pt.ax, &user->regs.eax);
132 put_user_ex(regs->pt.ip, &user->regs.eip);
133 put_user_ex(regs->pt.cs, &user->regs.cs);
134 put_user_ex(regs->pt.flags, &user->regs.eflags);
135 put_user_ex(regs->pt.sp, &user->regs.esp);
136 put_user_ex(regs->pt.ss, &user->regs.ss);
137 put_user_ex(regs->es, &user->regs.es);
138 put_user_ex(regs->ds, &user->regs.ds);
139 put_user_ex(regs->fs, &user->regs.fs);
140 put_user_ex(regs->gs, &user->regs.gs);
142 put_user_ex(vm86->screen_bitmap, &user->screen_bitmap);
143 } put_user_catch(err);
145 pr_alert("could not access userspace vm86 info\n");
149 tss = &per_cpu(cpu_tss, get_cpu());
150 tsk->thread.sp0 = vm86->saved_sp0;
151 tsk->thread.sysenter_cs = __KERNEL_CS;
152 load_sp0(tss, &tsk->thread);
153 refresh_sysenter_cs(&tsk->thread);
157 memcpy(®s->pt, &vm86->regs32, sizeof(struct pt_regs));
159 lazy_load_gs(vm86->regs32.gs);
161 regs->pt.ax = retval;
164 static void mark_screen_rdonly(struct mm_struct *mm)
166 struct vm_area_struct *vma;
175 down_write(&mm->mmap_sem);
176 pgd = pgd_offset(mm, 0xA0000);
177 if (pgd_none_or_clear_bad(pgd))
179 p4d = p4d_offset(pgd, 0xA0000);
180 if (p4d_none_or_clear_bad(p4d))
182 pud = pud_offset(p4d, 0xA0000);
183 if (pud_none_or_clear_bad(pud))
185 pmd = pmd_offset(pud, 0xA0000);
187 if (pmd_trans_huge(*pmd)) {
188 vma = find_vma(mm, 0xA0000);
189 split_huge_pmd(vma, pmd, 0xA0000);
191 if (pmd_none_or_clear_bad(pmd))
193 pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl);
194 for (i = 0; i < 32; i++) {
195 if (pte_present(*pte))
196 set_pte(pte, pte_wrprotect(*pte));
199 pte_unmap_unlock(pte, ptl);
201 up_write(&mm->mmap_sem);
202 flush_tlb_mm_range(mm, 0xA0000, 0xA0000 + 32*PAGE_SIZE, 0UL);
207 static int do_vm86_irq_handling(int subfunction, int irqnumber);
208 static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus);
210 SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, user_vm86)
212 return do_sys_vm86((struct vm86plus_struct __user *) user_vm86, false);
216 SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg)
219 case VM86_REQUEST_IRQ:
221 case VM86_GET_IRQ_BITS:
222 case VM86_GET_AND_RESET_IRQ:
223 return do_vm86_irq_handling(cmd, (int)arg);
224 case VM86_PLUS_INSTALL_CHECK:
226 * NOTE: on old vm86 stuff this will return the error
227 * from access_ok(), because the subfunction is
228 * interpreted as (invalid) address to vm86_struct.
229 * So the installation check works.
234 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
235 return do_sys_vm86((struct vm86plus_struct __user *) arg, true);
239 static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus)
241 struct tss_struct *tss;
242 struct task_struct *tsk = current;
243 struct vm86 *vm86 = tsk->thread.vm86;
244 struct kernel_vm86_regs vm86regs;
245 struct pt_regs *regs = current_pt_regs();
246 unsigned long err = 0;
248 err = security_mmap_addr(0);
251 * vm86 cannot virtualize the address space, so vm86 users
252 * need to manage the low 1MB themselves using mmap. Given
253 * that BIOS places important data in the first page, vm86
254 * is essentially useless if mmap_min_addr != 0. DOSEMU,
255 * for example, won't even bother trying to use vm86 if it
256 * can't map a page at virtual address 0.
258 * To reduce the available kernel attack surface, simply
259 * disallow vm86(old) for users who cannot mmap at va 0.
261 * The implementation of security_mmap_addr will allow
262 * suitably privileged users to map va 0 even if
263 * vm.mmap_min_addr is set above 0, and we want this
264 * behavior for vm86 as well, as it ensures that legacy
265 * tools like vbetool will not fail just because of
268 pr_info_once("Denied a call to vm86(old) from %s[%d] (uid: %d). Set the vm.mmap_min_addr sysctl to 0 and/or adjust LSM mmap_min_addr policy to enable vm86 if you are using a vm86-based DOS emulator.\n",
269 current->comm, task_pid_nr(current),
270 from_kuid_munged(&init_user_ns, current_uid()));
275 if (!(vm86 = kzalloc(sizeof(*vm86), GFP_KERNEL)))
277 tsk->thread.vm86 = vm86;
282 if (!access_ok(VERIFY_READ, user_vm86, plus ?
283 sizeof(struct vm86_struct) :
284 sizeof(struct vm86plus_struct)))
287 memset(&vm86regs, 0, sizeof(vm86regs));
290 get_user_ex(vm86regs.pt.bx, &user_vm86->regs.ebx);
291 get_user_ex(vm86regs.pt.cx, &user_vm86->regs.ecx);
292 get_user_ex(vm86regs.pt.dx, &user_vm86->regs.edx);
293 get_user_ex(vm86regs.pt.si, &user_vm86->regs.esi);
294 get_user_ex(vm86regs.pt.di, &user_vm86->regs.edi);
295 get_user_ex(vm86regs.pt.bp, &user_vm86->regs.ebp);
296 get_user_ex(vm86regs.pt.ax, &user_vm86->regs.eax);
297 get_user_ex(vm86regs.pt.ip, &user_vm86->regs.eip);
298 get_user_ex(seg, &user_vm86->regs.cs);
299 vm86regs.pt.cs = seg;
300 get_user_ex(vm86regs.pt.flags, &user_vm86->regs.eflags);
301 get_user_ex(vm86regs.pt.sp, &user_vm86->regs.esp);
302 get_user_ex(seg, &user_vm86->regs.ss);
303 vm86regs.pt.ss = seg;
304 get_user_ex(vm86regs.es, &user_vm86->regs.es);
305 get_user_ex(vm86regs.ds, &user_vm86->regs.ds);
306 get_user_ex(vm86regs.fs, &user_vm86->regs.fs);
307 get_user_ex(vm86regs.gs, &user_vm86->regs.gs);
309 get_user_ex(vm86->flags, &user_vm86->flags);
310 get_user_ex(vm86->screen_bitmap, &user_vm86->screen_bitmap);
311 get_user_ex(vm86->cpu_type, &user_vm86->cpu_type);
312 } get_user_catch(err);
316 if (copy_from_user(&vm86->int_revectored,
317 &user_vm86->int_revectored,
318 sizeof(struct revectored_struct)))
320 if (copy_from_user(&vm86->int21_revectored,
321 &user_vm86->int21_revectored,
322 sizeof(struct revectored_struct)))
325 if (copy_from_user(&vm86->vm86plus, &user_vm86->vm86plus,
326 sizeof(struct vm86plus_info_struct)))
328 vm86->vm86plus.is_vm86pus = 1;
330 memset(&vm86->vm86plus, 0,
331 sizeof(struct vm86plus_info_struct));
333 memcpy(&vm86->regs32, regs, sizeof(struct pt_regs));
334 vm86->user_vm86 = user_vm86;
337 * The flags register is also special: we cannot trust that the user
338 * has set it up safely, so this makes sure interrupt etc flags are
339 * inherited from protected mode.
341 VEFLAGS = vm86regs.pt.flags;
342 vm86regs.pt.flags &= SAFE_MASK;
343 vm86regs.pt.flags |= regs->flags & ~SAFE_MASK;
344 vm86regs.pt.flags |= X86_VM_MASK;
346 vm86regs.pt.orig_ax = regs->orig_ax;
348 switch (vm86->cpu_type) {
350 vm86->veflags_mask = 0;
353 vm86->veflags_mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL;
356 vm86->veflags_mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
359 vm86->veflags_mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
366 vm86->saved_sp0 = tsk->thread.sp0;
367 lazy_save_gs(vm86->regs32.gs);
369 tss = &per_cpu(cpu_tss, get_cpu());
370 /* make room for real-mode segments */
371 tsk->thread.sp0 += 16;
373 if (static_cpu_has(X86_FEATURE_SEP)) {
374 tsk->thread.sysenter_cs = 0;
375 refresh_sysenter_cs(&tsk->thread);
378 load_sp0(tss, &tsk->thread);
381 if (vm86->flags & VM86_SCREEN_BITMAP)
382 mark_screen_rdonly(tsk->mm);
384 memcpy((struct kernel_vm86_regs *)regs, &vm86regs, sizeof(vm86regs));
389 static inline void set_IF(struct kernel_vm86_regs *regs)
391 VEFLAGS |= X86_EFLAGS_VIF;
394 static inline void clear_IF(struct kernel_vm86_regs *regs)
396 VEFLAGS &= ~X86_EFLAGS_VIF;
399 static inline void clear_TF(struct kernel_vm86_regs *regs)
401 regs->pt.flags &= ~X86_EFLAGS_TF;
404 static inline void clear_AC(struct kernel_vm86_regs *regs)
406 regs->pt.flags &= ~X86_EFLAGS_AC;
410 * It is correct to call set_IF(regs) from the set_vflags_*
411 * functions. However someone forgot to call clear_IF(regs)
412 * in the opposite case.
413 * After the command sequence CLI PUSHF STI POPF you should
414 * end up with interrupts disabled, but you ended up with
415 * interrupts enabled.
416 * ( I was testing my own changes, but the only bug I
417 * could find was in a function I had not changed. )
421 static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs)
423 set_flags(VEFLAGS, flags, current->thread.vm86->veflags_mask);
424 set_flags(regs->pt.flags, flags, SAFE_MASK);
425 if (flags & X86_EFLAGS_IF)
431 static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs)
433 set_flags(VFLAGS, flags, current->thread.vm86->veflags_mask);
434 set_flags(regs->pt.flags, flags, SAFE_MASK);
435 if (flags & X86_EFLAGS_IF)
441 static inline unsigned long get_vflags(struct kernel_vm86_regs *regs)
443 unsigned long flags = regs->pt.flags & RETURN_MASK;
445 if (VEFLAGS & X86_EFLAGS_VIF)
446 flags |= X86_EFLAGS_IF;
447 flags |= X86_EFLAGS_IOPL;
448 return flags | (VEFLAGS & current->thread.vm86->veflags_mask);
451 static inline int is_revectored(int nr, struct revectored_struct *bitmap)
453 return test_bit(nr, bitmap->__map);
456 #define val_byte(val, n) (((__u8 *)&val)[n])
458 #define pushb(base, ptr, val, err_label) \
462 if (put_user(__val, base + ptr) < 0) \
466 #define pushw(base, ptr, val, err_label) \
470 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
473 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
477 #define pushl(base, ptr, val, err_label) \
481 if (put_user(val_byte(__val, 3), base + ptr) < 0) \
484 if (put_user(val_byte(__val, 2), base + ptr) < 0) \
487 if (put_user(val_byte(__val, 1), base + ptr) < 0) \
490 if (put_user(val_byte(__val, 0), base + ptr) < 0) \
494 #define popb(base, ptr, err_label) \
497 if (get_user(__res, base + ptr) < 0) \
503 #define popw(base, ptr, err_label) \
506 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
509 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
515 #define popl(base, ptr, err_label) \
518 if (get_user(val_byte(__res, 0), base + ptr) < 0) \
521 if (get_user(val_byte(__res, 1), base + ptr) < 0) \
524 if (get_user(val_byte(__res, 2), base + ptr) < 0) \
527 if (get_user(val_byte(__res, 3), base + ptr) < 0) \
533 /* There are so many possible reasons for this function to return
534 * VM86_INTx, so adding another doesn't bother me. We can expect
535 * userspace programs to be able to handle it. (Getting a problem
536 * in userspace is always better than an Oops anyway.) [KD]
538 static void do_int(struct kernel_vm86_regs *regs, int i,
539 unsigned char __user *ssp, unsigned short sp)
541 unsigned long __user *intr_ptr;
542 unsigned long segoffs;
543 struct vm86 *vm86 = current->thread.vm86;
545 if (regs->pt.cs == BIOSSEG)
547 if (is_revectored(i, &vm86->int_revectored))
549 if (i == 0x21 && is_revectored(AH(regs), &vm86->int21_revectored))
551 intr_ptr = (unsigned long __user *) (i << 2);
552 if (get_user(segoffs, intr_ptr))
554 if ((segoffs >> 16) == BIOSSEG)
556 pushw(ssp, sp, get_vflags(regs), cannot_handle);
557 pushw(ssp, sp, regs->pt.cs, cannot_handle);
558 pushw(ssp, sp, IP(regs), cannot_handle);
559 regs->pt.cs = segoffs >> 16;
561 IP(regs) = segoffs & 0xffff;
568 save_v86_state(regs, VM86_INTx + (i << 8));
571 int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno)
573 struct vm86 *vm86 = current->thread.vm86;
575 if (vm86->vm86plus.is_vm86pus) {
576 if ((trapno == 3) || (trapno == 1)) {
577 save_v86_state(regs, VM86_TRAP + (trapno << 8));
580 do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs));
584 return 1; /* we let this handle by the calling routine */
585 current->thread.trap_nr = trapno;
586 current->thread.error_code = error_code;
587 force_sig(SIGTRAP, current);
591 void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code)
593 unsigned char opcode;
594 unsigned char __user *csp;
595 unsigned char __user *ssp;
596 unsigned short ip, sp, orig_flags;
597 int data32, pref_done;
598 struct vm86plus_info_struct *vmpi = ¤t->thread.vm86->vm86plus;
600 #define CHECK_IF_IN_TRAP \
601 if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \
602 newflags |= X86_EFLAGS_TF
604 orig_flags = *(unsigned short *)®s->pt.flags;
606 csp = (unsigned char __user *) (regs->pt.cs << 4);
607 ssp = (unsigned char __user *) (regs->pt.ss << 4);
614 switch (opcode = popb(csp, ip, simulate_sigsegv)) {
615 case 0x66: /* 32-bit data */ data32 = 1; break;
616 case 0x67: /* 32-bit address */ break;
617 case 0x2e: /* CS */ break;
618 case 0x3e: /* DS */ break;
619 case 0x26: /* ES */ break;
620 case 0x36: /* SS */ break;
621 case 0x65: /* GS */ break;
622 case 0x64: /* FS */ break;
623 case 0xf2: /* repnz */ break;
624 case 0xf3: /* rep */ break;
625 default: pref_done = 1;
627 } while (!pref_done);
634 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv);
637 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv);
641 goto vm86_fault_return;
646 unsigned long newflags;
648 newflags = popl(ssp, sp, simulate_sigsegv);
651 newflags = popw(ssp, sp, simulate_sigsegv);
657 set_vflags_long(newflags, regs);
659 set_vflags_short(newflags, regs);
666 int intno = popb(csp, ip, simulate_sigsegv);
668 if (vmpi->vm86dbg_active) {
669 if ((1 << (intno & 7)) & vmpi->vm86dbg_intxxtab[intno >> 3]) {
670 save_v86_state(regs, VM86_INTx + (intno << 8));
674 do_int(regs, intno, ssp, sp);
683 unsigned long newflags;
685 newip = popl(ssp, sp, simulate_sigsegv);
686 newcs = popl(ssp, sp, simulate_sigsegv);
687 newflags = popl(ssp, sp, simulate_sigsegv);
690 newip = popw(ssp, sp, simulate_sigsegv);
691 newcs = popw(ssp, sp, simulate_sigsegv);
692 newflags = popw(ssp, sp, simulate_sigsegv);
699 set_vflags_long(newflags, regs);
701 set_vflags_short(newflags, regs);
710 goto vm86_fault_return;
714 * Damn. This is incorrect: the 'sti' instruction should actually
715 * enable interrupts after the /next/ instruction. Not good.
717 * Probably needs some horsing around with the TF flag. Aiee..
725 save_v86_state(regs, VM86_UNKNOWN);
731 if (VEFLAGS & X86_EFLAGS_VIP) {
732 save_v86_state(regs, VM86_STI);
737 if (vmpi->force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) {
738 save_v86_state(regs, VM86_PICRETURN);
741 if (orig_flags & X86_EFLAGS_TF)
742 handle_vm86_trap(regs, 0, X86_TRAP_DB);
746 /* FIXME: After a long discussion with Stas we finally
747 * agreed, that this is wrong. Here we should
748 * really send a SIGSEGV to the user program.
749 * But how do we create the correct context? We
750 * are inside a general protection fault handler
751 * and has just returned from a page fault handler.
752 * The correct context for the signal handler
753 * should be a mixture of the two, but how do we
754 * get the information? [KD]
756 save_v86_state(regs, VM86_UNKNOWN);
759 /* ---------------- vm86 special IRQ passing stuff ----------------- */
761 #define VM86_IRQNAME "vm86irq"
763 static struct vm86_irqs {
764 struct task_struct *tsk;
768 static DEFINE_SPINLOCK(irqbits_lock);
771 #define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \
772 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \
775 static irqreturn_t irq_handler(int intno, void *dev_id)
780 spin_lock_irqsave(&irqbits_lock, flags);
781 irq_bit = 1 << intno;
782 if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk)
785 if (vm86_irqs[intno].sig)
786 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1);
788 * IRQ will be re-enabled when user asks for the irq (whether
789 * polling or as a result of the signal)
791 disable_irq_nosync(intno);
792 spin_unlock_irqrestore(&irqbits_lock, flags);
796 spin_unlock_irqrestore(&irqbits_lock, flags);
800 static inline void free_vm86_irq(int irqnumber)
804 free_irq(irqnumber, NULL);
805 vm86_irqs[irqnumber].tsk = NULL;
807 spin_lock_irqsave(&irqbits_lock, flags);
808 irqbits &= ~(1 << irqnumber);
809 spin_unlock_irqrestore(&irqbits_lock, flags);
812 void release_vm86_irqs(struct task_struct *task)
815 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++)
816 if (vm86_irqs[i].tsk == task)
820 static inline int get_and_reset_irq(int irqnumber)
826 if (invalid_vm86_irq(irqnumber)) return 0;
827 if (vm86_irqs[irqnumber].tsk != current) return 0;
828 spin_lock_irqsave(&irqbits_lock, flags);
829 bit = irqbits & (1 << irqnumber);
832 enable_irq(irqnumber);
836 spin_unlock_irqrestore(&irqbits_lock, flags);
841 static int do_vm86_irq_handling(int subfunction, int irqnumber)
844 switch (subfunction) {
845 case VM86_GET_AND_RESET_IRQ: {
846 return get_and_reset_irq(irqnumber);
848 case VM86_GET_IRQ_BITS: {
851 case VM86_REQUEST_IRQ: {
852 int sig = irqnumber >> 8;
853 int irq = irqnumber & 255;
854 if (!capable(CAP_SYS_ADMIN)) return -EPERM;
855 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM;
856 if (invalid_vm86_irq(irq)) return -EPERM;
857 if (vm86_irqs[irq].tsk) return -EPERM;
858 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL);
860 vm86_irqs[irq].sig = sig;
861 vm86_irqs[irq].tsk = current;
864 case VM86_FREE_IRQ: {
865 if (invalid_vm86_irq(irqnumber)) return -EPERM;
866 if (!vm86_irqs[irqnumber].tsk) return 0;
867 if (vm86_irqs[irqnumber].tsk != current) return -EPERM;
868 free_vm86_irq(irqnumber);